| 英文摘要 |
Polylactic acid (PLA) consumption is increasing in recent years, mostly one time use packaging materials. About 1600 tons/year of post-consumer PLA wastes are generated in Taiwan. From 2010, PLA has been regulated by Taiwan’s EPA as a recyclable item. However, the collected PLA wastes are often mixed together with PET, PE or PS. The separation process of “post-consumer” wastes is the most complex and results in high impurities in PLA recycle stream, compared to that of “post-industrial” or “short-loop” wastes. Moreover, the collected PLA wastes are typically deteriorated and further causion needs to be paid for processing. Until now, no industrial separation process has been made to separate PLA from municipal solid waste (MSW). There are also few reports on the assessment of the properties of recycled PLA from post-consumer garbage. In this project, we report the separation and recycling process of PLA from MSW recycling system, including human sorting, float-sink sorting and NIR sorting. The purity of the PLA waste after serial sorting and recycling process was higher than 97%; however, the molecular weight of the recycled and processed PLA flakes were typically downgraded from 150,000 of neat PLA to 60,000 ~ 100,000. The tensile strength and impact strength of recycled PLA were about half of neat PLA. By adding neat PLA resin (1:1 ratio to recycled PLA), commercial chain extender ADR-4370S (BASF) as well as ITRI-developed nano organic/inorganic hybrid nucleating aget, mechanical properties of the formulated recycled PLA were enhanced to the follows tensile strength > 550kgf/cm2, flexural strength>900kgf/cm2 and impact strength >0 .5 ft-lb/in, which were close to neat PLA. The HDT of the formulated recycled PLA were improved from 55℃to >90℃ by thermal annealing of the injected object at 100~110℃for 60s.
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